Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < (n); ++i)
using namespace std;
typedef long long ll;
typedef pair <int,int> P;

int d[55][55];

int main() {
  int h,w;
  cin>>h>>w;
  char s[55][55];
  int cnt=0;
  rep(i,h) rep(j,w) {
    cin>>s[i][j];
    if (s[i][j]=='#') cnt++;
  }
  queue<P> q;
  q.push({0,0});
  d[0][0]=1;
  int dx[4] = {1,0,-1,0};
  int dy[4] = {0,1,0,-1};
  while (!q.empty()) {
    int x,y;
    tie(x,y)=q.front(); q.pop();
    rep(i,4) {
      int nx=x+dx[i],ny=y+dy[i];
      if (nx>=0&&nx<h&&ny>=0&&ny<w) {
	if (!d[nx][ny]&&s[nx][ny]=='.') {
	  d[nx][ny]=d[x][y]+1;
	  q.push({nx,ny});
	}
      }
    }
  }
  if (d[h-1][w-1]==0) cout<<-1<<endl;
  else cout<<h*w-d[h-1][w-1]-cnt<<endl;
  return 0;
}